Holzman said the schools were under a perimeter lockdown from 9:45 a.m. until about 11:30 a.m. Thursday while the Manitowoc Police Department and the Brown County Sheriff’s Department investigated the nature of the threat.

The comings and goings of staff and students were restricted and no outside recess was allowed during the lockdown.

“Our people did a great job in following the procedures,” Holzman said.

According to Holzman, parents of the students at each school will receive a notice of the lockdown.